Hello everybody,
I would know, why on kicad i can’t place a VIA exactly under a pad of BGA ? If i do this, the VIA is delete by the function “Edit->Cleanup Tracks and Vias” I don’t understand why.
Is there a raison for this ? Is There a specific VIA to achieve this ?
I placed a VIA between two pad but it’s not optimized, I could reduce the size of the tracks for pass between two pads but make a VIA under a pad of BGA it’s better.
Thanks.
PS: Sorry my English isn’t good enough.
Is this a thermal via? If so I normally use drills in the footprint for
those.
Thank you for the answer.
It’s not a thermal via.
You’re not supposed to put a normal via directly into a pad of a BGA. What will happen during reflow is that the solder will wick into the through plated via and flow away from the balls of the BGA and therefore the ball of the BGA won’t be properly soldered.
If there’s absolutely no other choice then you’ll have to use a plugged (what’s the correct term here?) via, essentially a normal via that then get’s plugged up with solder resist in a separate manufacturing step. This prevents the solder/solder paste from flowing into the via and away from the pad.
Thanks.
I made a mistake, it’s not BGA but LGA.
Is what you say still true?
Essentially the same thing is going to happen always when you put a via into a pad, it’s bad practice for the exact same reasons and should be avoided if possible.
An extra manufacturing step (needing to plug the vias) will add cost to the PCBs.
It is plugging (often with non-conductive epoxy) AND surface leveling after that.